SK Fung handles rooftop glass house design, glass roofs, glass canopies, rain shelters, awnings, pergolas, roof railings, prefabricated cabins, rooftop storage rooms and custom storage cabinets. We advise on the actual structure, waterproofing, drainage and ventilation requirements.
Free on-site measurement, design and quotations. Call 3709 2164 or WhatsApp 6686 7879 to enquire.
Buildings Department Registered Minor Works Contractor MWC(W) 42/2014, with window inspection qualifications. Our technicians hold Construction Industry Council aluminium window skills certificates. Rooftop works are subject to the Buildings Ordinance; review the approval requirements and minor works submission procedures before starting.
Service Overview
SK Fung specialises in rooftop glass house design, prefabricated cabins and storage cabinets for leisure, storage or small workspaces. We advise on the existing structure, waterproofing and ventilation, and provide repair and maintenance services.
The main uncertainty in these works is legality. Glass houses on main roofs, flat roofs or light wells require prior approval and consent, coordination by an Authorized Person and construction by a Registered General Building Contractor. Since April 2011, rooftop unauthorised structures have been prioritised for enforcement regardless of age or risk. We explain the required procedures before discussing design and quotations.
Legal Requirements
The following guidance is compiled from public information issued by the Buildings Department, Development Bureau and Legislative Council. Read it before starting work.
The exemption under section 41(3) of the Buildings Ordinance applies only to works inside a building that do not involve its structure. The Government has clarified that rooftop additions are not considered works inside a building; erecting them without prior approval is therefore unauthorised building work. Even exempt works must meet applicable fire safety, structural safety, drainage and other building standards.
From 1 April 2011, enhanced enforcement covers all unauthorised structures on main roofs, flat roofs, light wells and rear lanes, regardless of public safety risk or whether they are new or existing. After inspection, the Buildings Department first issues an advisory letter urging rectification. If work does not begin within the specified time, it may issue a statutory removal order and register it at the Land Registry. Reports are prioritised according to public safety risk and the date received.
The Buildings Department checks new unauthorised structures using aerial photographs, building photographic records, enquiries and circumstantial evidence. Being invisible from street level does not prevent detection. The Department has also stated that payment of property tax or rates does not legalise an unauthorised structure.
For prefabricated storage cabinets on main roofs, flat roofs or light wells with volume not exceeding 3 cubic metres and height not exceeding 2 metres, owners must ensure stability and meet three conditions:
Larger cabinets and cabins exceeding the volume or height limits require the prior-approval procedure described above.
Arrange rectification promptly in accordance with any statutory order. Owners facing financial difficulty may apply under the Buildings Department's Building Safety Loan Scheme for necessary compliance works. Removal of unauthorised structures on roofs, flat roofs, light wells and rear lanes is itself a minor works category, including Class I item 1.38, Class II item 2.39 and Class III item 3.32, subject to the relevant contractor registration.
This summary of public information is for reference and is not legal advice. Applicable requirements depend on the Buildings Department and the appointed Authorized Person's professional assessment. SK Fung can advise on glass and aluminium components and help clarify the appropriate procedure.
Minor Works Control System
Each type of rooftop or outdoor work has its own statutory procedure; not every item requires full building-plan approval.
The Minor Works Control System was fully implemented on 31 December 2010 to allow safe, lawful small-scale building works through simplified procedures. It regulates 187 items: 58 Class I items, 68 Class II items and 61 Class III items, categorised by scale, complexity and safety risk. Amendments in 2012 added eight items; amendments effective 1 September 2020 repealed nine, amended 56 and added 70 items.
| Class | Required Appointments | Before Commencement | After Completion |
|---|---|---|---|
| Class I · 58 Items | Prescribed building professionals—Authorized Person or Registered Inspector, with a Registered Structural Engineer or Registered Geotechnical Engineer where required—and a prescribed registered contractor | Submit commencement notice MW01 or MW03, prescribed plans and details at least 7 days beforehand; some items also require a supervision plan | Submit completion certificate MW02 or MW04 and record plans within 14 days |
| Class II · 68 Items | Prescribed Registered Contractor | Submit commencement notice MW01 or MW03, prescribed plans and details at least 7 days beforehand | Submit completion certificate MW02 or MW04 and record plans within 14 days |
| Class III · 61 Items | Prescribed Registered Contractor | No advance submission; work may commence directly | Submit completion certificate MW05, plans or a description and photographs within 14 days |
All three classes do not require prior approval of plans and consent to commencement under section 14(1). Required photographs must show actual conditions before and after the works.
| Type of Work | Item Numbers by Class |
|---|---|
| Erection, alteration, repair or removal of canopies and retractable awnings | Class I 1.27; Class II 2.31, 2.43; Class III 3.25, 3.26, 3.38, 3.43 |
| Erection, alteration, repair or removal of pergolas | Class I 1.45; Class II 2.44, 2.45; Class III 3.44 |
| Solid roof walls | Class I 1.55; Class II 2.55, 2.61, 2.64; Class III 3.55, 3.61, 3.64 |
| Roof mesh fences or metal railings | Class I 1.56; Class II 2.56, 2.62, 2.65; Class III 3.56, 3.62, 3.65 |
| Roof posts | Class I 1.54; Class II 2.54, 2.60, 2.63; Class III 3.54, 3.60, 3.63 |
| Construction, alteration, repair, removal or replacement of windows and glass external walls | Class I 1.60; Class II 2.8, 2.9; Class III 3.6, 3.7 |
| Erection, alteration, removal, repair or replacement of protective barriers | Class I 1.6; Class II 2.5; Class III 3.3 |
| Removal of unauthorised structures on roofs, flat roofs, light wells and rear lanes | Class I 1.38; Class II 2.39; Class III 3.32 |
Classification depends on dimensions, position and structural conditions, such as cantilevered slabs, additional slab loads or changes to other structural members. Appointed professionals and contractors must meet every applicable requirement. See Aluminium Windows & Doors for window and glazed-wall works, and Glass Balustrades for protective barriers.
The system includes 30 designated exempted works of lower complexity and risk. These do not require prior plan approval, written consent or appointment of an Authorized Person and registered contractor. Roof and outdoor examples include:
Designated exemption still requires compliance with the building design and construction standards under the Buildings Ordinance; non-compliant work may remain unauthorised.
Registered Minor Works Contractors (Companies) are registered under Types A to H: A alteration and addition, B repair, C signboards, D drainage, E amenity features, F finishes, G demolition and H internal ventilation. Self-employed practitioners may register as individual contractors for Class III items 3.1–3.66. Verify the contractor's classes, types and items cover the work. Works in common parts, such as external walls and the main roof, require consent from all co-owners or the owners' corporation and management company and compliance with the deed of mutual covenant.
The system also includes the Household Minor Works Validation Scheme, Minor Amenity Feature Validation Scheme and Signboard Validation Scheme for qualifying small, low-risk installations constructed before the schemes took effect. Glass houses and large rooftop structures do not fall into these small, low-risk categories.
Types of Work
Aluminium structures with glazing for leisure or small workspaces. Prior approval is required, with an Authorized Person coordinating and a Registered General Building Contractor carrying out the work.
Glazing over light wells, stairs or atriums to admit daylight. Overhead glass generally uses laminated glazing, with spans, loading and drainage falls assessed.
Weather protection for entrances, stairs or terraces. Canopies and retractable awnings are minor works categories; those not more than 3 metres above ground or roof level may qualify as designated exempted works.
Garden or terrace shade and climbing-plant structures, classified under pergola items 1.45, 2.44, 2.45 and 3.44 according to size and location.
Roof-edge protection. Structures not exceeding 1.1 metres high without a solid base wall may be designated exempted works; larger structures are classified under the relevant items.
Modular structures used for storage or tool rooms. Volume over 3 cubic metres or height over 2 metres requires prior approval.
Prefabricated cabinets not exceeding 3 cubic metres and 2 metres high must be stable, protect the structure, preserve escape routes and avoid affecting drainage.
Repair of existing silicone joints, seals, outlets and flashings. Applicable procedures depend on the actual repair item and location.
Design Priorities
Hong Kong glass houses must address heavy rain, afternoon sun and typhoons together.
The roof needs sufficient fall towards outlets, whose number and position must match the catchment area and discharge route. Insufficient fall and poorly placed outlets cause ponding and prolonged pressure on joints. Gutters need cleaning access to prevent leaves and dirt causing backflow indoors.
Connections with existing walls and parapets need upturned flashings and reliable joint detailing. Silicone alone is insufficient: it ages under UV exposure and temperature changes. Drainage, overlaps and flashings should provide the waterproofing, with silicone as a supplementary seal.
Overheating is a common complaint. Low-level opening panels and high-level exhaust openings or mechanical extraction create a path for hot air. A few side windows may be insufficient on summer afternoons. Calculate the opening area during design where the space is used for living.
Low-E glazing reduces radiant heat, while insulating double glazing reduces conduction. External shading, louvres or blinds intercept heat before it passes through glass and are more effective than internal curtains. Combine these measures with ventilation.
Frame cross-sections, wall thickness, support spacing, connections and base fixings must account for span, glass weight, wind loading and corrosion. This structural assessment is why rooftop glass houses require professional coordination and a Registered General Building Contractor; experience cannot replace calculations.
Material Specifications
| Glass | Properties | Typical glass house applications |
|---|---|---|
| Laminated glass | The interlayer holds fragments together if the glass breaks. | Preferred for roofs, skylights and overhead glazing. |
| Toughened (tempered) glass | Higher strength; breaks into small particles. | Side elevations; specify heat-soaked glass where appropriate. |
| Double glazing | An air gap reduces heat transfer and condensation. | Glass houses used as living spaces with temperature control. |
| Low-E glass | A coating reflects infrared radiation and reduces radiant heat. | West-facing elevations and large glazed roofs. |
| Frosted / translucent glass | Softens light and improves privacy. | Elevations facing neighbours or bathrooms. |
| Acoustic glass | Reduces environmental noise. | Rooftops overlooking streets or main roads. |
Prefabricated cabins · Storage
Prefabricated cabins generally use metal panels or prefabricated components for quick assembly, durability and storage. Glass houses use glass and aluminium for daylight, waterproofing and thermal comfort. Both are regulated: prefabricated cabins or large storage cabinets exceeding 3 cubic metres or 2 metres in height, and glass houses on main roofs, flat roofs or light wells, require prior Buildings Department approval and consent.
Plan interior cabinets, glass finishes and mirrors together. See interior mirror decoration and glass partitions.
Problem diagnosis
Repeated waterproofing will not solve a problem diagnosed incorrectly.
Insufficient fall or poorly positioned outlets leave water stains and persistently wet joints after rain. Correct the drainage design rather than simply adding sealant.
Aged or cracked silicone, deteriorated gaskets or inadequate overlaps cause dripping at fixed locations during rain. Remove old sealant, reseal and check the waterproofing detail.
Inadequate flashing where the roof meets a parapet or existing wall causes water tracks along the wall. Renew the junction and flashing.
Leaves and dirt raise water levels and cause backflow. Cleaning before the rainy season helps prevent this maintenance problem.
Evenly distributed droplets inside the glass during temperature changes indicate inadequate ventilation rather than rainwater leakage. Improve exhaust ventilation and consider double glazing.
Insufficient high-level exhaust openings and external shading trap heat. Add ventilation and external shading, or consider Low-E or double glazing.
Our process
Maintenance
During the same visit, we can check window seals and waterproofing, rooftop balustrade fixings and insect and safety screens to reduce repeat arrangements.
Service coverage
Our office is at Room F11, 10/F, How Ming Factory Building, 99 How Ming Street, Kwun Tong, Hong Kong. We serve Hong Kong Island, Kowloon and the New Territories.
Frequently Asked Questions
30 questions covering approval, minor works procedures, materials, leaks, overheating, quotations and maintenance.
Yes. The Buildings Department requires prior approval and consent for glass houses and specified prefabricated structures on main roofs, flat roofs or light wells, including cabins and large storage cabinets exceeding 3 cubic metres or 2 metres high. An Authorized Person submits plans and coordinates the works; a Registered General Building Contractor undertakes construction after approval. Unauthorized construction is subject to enforcement.
Not for these glass houses or large prefabricated rooftop structures. They require an Authorized Person and Registered General Building Contractor. As a Registered Minor Works Contractor, MWC(W) 42/2014, SK Fung helps clarify the procedure and can undertake relevant minor works within its registered scope and coordinate glass and aluminium work.
Section 41(3) covers non-structural works inside a building. Rooftop structures are not considered inside the building and require prior approval where applicable. Even exempt works must meet the building standards under the Buildings Ordinance and its regulations.
Since 1 April 2011, priority enforcement has included all unauthorized structures on roofs, flat roofs, light wells and rear lanes, regardless of risk or age. Following inspection, the Department may issue an advisory letter, then a statutory removal order if not rectified in time. The order is registered at the Land Registry.
It compares aerial photographs, retains building photograph records and considers enquiries and circumstantial evidence. Structures hidden from street view can still be detected through aerial comparisons.
No. Payment does not legalize an unauthorized structure. Legality depends on the required Buildings Ordinance approval and consent, or compliance with applicable exemptions or minor works procedures.
A prefabricated cabinet not exceeding 3 cubic metres and 2 metres high on a main roof, flat roof or light well must be stable, protect structural safety, keep escape and refuge areas clear, and preserve drainage. Larger cabinets or cabins require prior approval and consent.
Implemented on 31 December 2010, the system regulates 187 items: 58 Class I, 68 Class II and 61 Class III, according to scale, complexity and risk. Regulations were amended in 2012 and 2020; amendments effective on 1 September 2020 repealed 9 items, amended 56 and added 70.
Class I requires prescribed building professionals and contractors, MW01 / MW03 submissions at least 7 days before commencement, and MW02 / MW04 within 14 days after completion. Class II requires prescribed contractors and 7-day advance notice. Class III requires prescribed contractors, with MW05, plans or descriptions and photographs within 14 days after completion. None requires prior approval of plans and consent to commence.
Yes. Erection, alteration, repair and removal are classified by size and location, including items 1.27, 2.31, 2.43, 3.25, 3.26, 3.38 and 3.43. Certain canopies within 3 metres of ground or roof level are among the 30 designated exempted works: no prior approval or appointment of an Authorized Person and registered contractor is required, but building standards still apply.
These are classified minor works, including solid walls (1.55 / 2.55 / 3.55), mesh fences or metal barriers (1.56 / 2.56 / 3.56), and posts (1.54 / 2.54 / 3.54). Designated exemptions include qualifying non-solid barriers up to 1.1 metres high, posts up to 1.1 metres, and solid walls up to 500 mm on roofs.
Registered Minor Works Contractors (Companies) register for classes and one or more of eight types: A alteration and addition, B repair, C signage, D drainage, E amenity features, F finishes, G demolition and H ventilation systems inside buildings. Individuals may register for Class III items 3.1–3.66. Check the appointed contractor's classes, types and items against the proposed work.
For works on common parts, such as external walls or main roofs, those arranging and undertaking the works must obtain the required consent of all co-owners or the owners' corporation and management company, and comply with the DMC. Ownership obligations apply alongside statutory requirements.
This depends on the case. Validation schemes cover qualifying small, lower-risk household installations, amenity features and signboards built before the relevant scheme commenced. Glass houses and large rooftop structures do not fall within these schemes; all rooftop unauthorized structures have been priority enforcement targets since April 2011.
Arrange rectification promptly and note that the order is registered at the Land Registry. Owners in financial difficulty can apply under the Building Safety Loan Scheme for eligible removal costs. Demolition of unauthorized structures on roofs, flat roofs, light wells and rear lanes is itself classified under minor works items 1.38, 2.39 and 3.32.
Laminated glass generally suits overhead locations because its interlayer retains fragments. Toughened glass has a small risk of spontaneous breakage from NiS inclusions; the 2018 structural glass code addresses heat-soak treatment. The responsible professional must determine specifications for span, loading and location.
Combine three measures: Low-E or double glazing; low-level intake and high-level exhaust or mechanical ventilation; and external shades, louvres or blinds. Any one measure alone has limited effect.
Common causes are inadequate roof fall or outlet placement, aged joint seals, poor wall or parapet flashing, blocked gutters and outlets, and slight structural deformation opening joints. First distinguish external water ingress from internal condensation.
Not necessarily. Evenly distributed droplets during temperature changes usually indicate condensation from indoor moisture on cold glass. Leaks follow particular joints, screws or corners during rain. Improve ventilation or consider double glazing for condensation; repair weatherproofing for leaks.
Calculate span, glass weight, wind pressure and any imposed loads to specify profile section, wall thickness, support spacing, connections and corrosion protection. Rooftop wind pressure makes anchors and bases especially important. An Authorized Person and relevant professionals must design and coordinate rooftop glass houses where required.
Yes. Openings are central to ventilation, typically combining low-level intake with high-level exhaust. Hinges, stays and locks must resist wind and frames need drainage holes. See the aluminium windows, sliding doors and folding doors page for related hardware and waterproofing details.
Glass houses emphasize daylight, waterproofing and insulation using glass and aluminium. Cabins typically use metal panels or prefabricated components for quick assembly, durability and storage. Both are regulated: the specified cabins and cabinets exceeding 3 cubic metres or 2 metres high, and glass houses on roofs, flat roofs or light wells, require prior approval and consent.
Provide a sloping roof, rain-resistant doors and joints, a raised base, ventilation and corrosion-resistant hardware. Do not damage the structure, obstruct escape routes or affect drainage.
We undertake applicable minor works within our registered classes and types, such as related canopies, rooftop barriers, aluminium windows, glazing and repairs. For glass houses or large rooftop structures requiring approval, owners should first appoint an Authorized Person and Registered General Building Contractor; we coordinate the glass and aluminium work.
Cost depends on area and span, glass type, aluminium profiles and structural complexity, openings, waterproofing and drainage, shading and ventilation, access, lifting, scaffolding or suspended platforms. Approval projects also involve professional fees and submission procedures. We offer free site measurement, design and quotations.
Rain and damp surfaces affect sealant adhesion; strong winds prevent safe handling of large panes. Programmes allow weather contingency and temporary covering during rainy periods. Include plan approval time where required.
This depends on location and component size. Roof-level access may suffice, but external lifting or work beyond the facade can require scaffolding or a suspended platform. Coordinate access, lifts, timing and safety with management; the quotation sets out the arrangements.
Inspect at least twice yearly, including before the rainy season. Clean outlets, gutters and debris; check seals for cracking or hardening, connections for looseness or corrosion, and opening hardware and drain holes. Use safe roof cleaning arrangements and never stand on glass.
We provide repair and maintenance for homes, village houses, owners' corporations and businesses. Coverage and duration depend on the project and specified glass, aluminium and hardware, and are stated in the quotation.
SK Fung is a Registered Minor Works Contractor, certificate MWC(W) 42/2014, with window inspection qualifications. Technicians hold Aluminium Window Skill Test certificates from the Construction Industry Council Training Academy. Browse glass house / prefabricated cabin photographs and compare our window, balustrade and partition projects.
Related pages
Explore glass house design, rooftop canopies and custom storage, with guidance on glazing, aluminium structures, waterproofing, drainage, ventilation, statutory procedures and ongoing maintenance throughout Hong Kong.
